cpu build help plz

Id like to get together a list of parts needed to put together a gaming cpu for under 1.2k ... if you guys can put together a build for a amd and a intel based computer . I would like for it to be able to play battlefield 3 on medium or high settings . Thx for the help

Thx

Budget- 1200
Resolution- best for price i guess .
Games / Settings Desired -Battlefield 3 Witcher 2 , World of warcraft , all atleast on medium settings
Any other intensive software or special things you do (Frequent video encoding, 3D modeling, etc)-just for gaming and regular browsing
Country- USA
Parts that can be reused - n/a